Switching and logic circuits provide waveforms which are the result of operations upon one or more input signals.
The current practice for this type of circuits is to operate them at full, range of available supply. The power consumption of such a circuit can be expressed by:Pdyn=CL×V2×f×αfrom which it is apparent that the power consumption of such circuits depends quadratically on the supply value (V), and linearly on capacitive load (CL), frequency of operation (f), and activity factor (α). The activity factor defines the ratio of the actual average number of transitions per second, divided by the maximum number of the same.
The disadvantage of this practice is the use of full supply range leading to unnecessarily high power consumption.